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From: David Gibson <david@gibson.dropbear.id.au>
To: linuxppc-embedded@lists.linuxppc.org
Subject: Re: CONFIG_PIN_TLB and telnet problems
Date: Fri, 31 May 2002 17:27:56 +1000	[thread overview]
Message-ID: <20020531072756.GG16537@zax> (raw)
In-Reply-To: <20020531071550.GF16537@zax>


On Fri, May 31, 2002 at 05:15:50PM +1000, David Gibson wrote:
>
> Ok, I think I've managed to reproduce the telnet problems with
> CONFIG_PIN_TLB that Tom Rini and others have reported.  I encountered
> problems telnetting to localhost on a 16MB EP405 (PVR 40110145) and on
> a 32MB Walnut (PVR 401100C4).  I was unable to reproduce the problem
> on any of the other 405GP machines I have, each of which as at least
> 64MB of RAM.
>
> Interestingly, if I alter the CONFIG_PIN_TLB code so that it only pins
> one entry (i.e. maps 16MB of RAM instead of 32MB) I can still
> reproduce the problem on the EP405, but not on the Walnut.  It would
> seem the problem only bites if the pinned allocation is as large or
> larger than physical memory.
>
> It's vaguely understandable that with two pinned entries it would
> break on the 16MB machine: creating a mapping for more RAM than exists
> is certainly a bug.  I don't yet know why there is a problem when the
> mapping is exactly as large as RAM though.

Update:  I've now also reproduced the problem on a 64MB EP405PC board,
by using mem=16M or mem=32M

--
David Gibson			| For every complex problem there is a
david@gibson.dropbear.id.au	| solution which is simple, neat and
				| wrong.  -- H.L. Mencken
http://www.ozlabs.org/people/dgibson

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

  reply	other threads:[~2002-05-31  7:27 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-05-31  7:15 CONFIG_PIN_TLB and telnet problems David Gibson
2002-05-31  7:27 ` David Gibson [this message]
2002-06-04  0:54 ` Dan Malek
2002-06-04  1:26   ` Paul Mackerras
2002-06-04 12:20     ` benh
2002-06-04 12:37       ` Benjamin Herrenschmidt

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